// https://github.com/thumbsupep/proposal-upsert
$({ target: 'Map', proto: true, real: true, forced: IS_PURE }, {
upsert: $upsert
// https://github.com/thumbsupep/proposal-upsert
$({ target: 'Map', proto: true, real: true, forced: IS_PURE }, {
upsert: $upsert